Method of electrolytically reproducing prints or designs



AJune 3, `947. C, o; PRE-ST v 2,421,735

METHOD 0F ELCTROLYTICALLY REPRODUCING PRINTS A0R DESIGNS F/G -lT O oo u E A@ W O v M@ @m CLARE/VCE 0;,0@

Patented June 3, 1947 METHOD F ELECTROLYTICALLY REPRO- DUCING PRINTS OR DESIGNS Clarence 0. Prest, Burbank, Calif.

Application December 22, 1941, Serial No. 423,997

Claims.

This invention relates to a method of reproducing prints or designs from one surface to another, and this application is a continuation-inpart of copending application Serial No. 332,077, led April 27, 1940, now Patent No. 2,306,082, granted December 22, 1942. It is particularly advantageous in producing reproductions of drawings, designs, templates, dies and the like, in connection with the aircraft or ship building industries wherein by reason of the high deg-ree of accuracy that can be attained by the method large, substantially flat, sheets of-metal are used as material upon which master layouts are drafted.

There is a great duplication of work in many industries because of the lack of a simple, cheap and accurate method of reproduction of such metal layout drawings. For instance, in the aircraft industry, the design of a particular part of the aircraft is made by the engineering department who, in turn, transmits such design to the factory for production. The factory or the engineering department usually drafts the part design drawing on the surface of metal sheets to form what is commonly known as the master template layout. This drawing may be made by scribing through Aa painted surface coating previously applied to the sheet metal by suitable means. In utilizing these master template layouts the factory must necessarily redraft the design usually on similar metal plates which are subsequently cut in order to form the necessary templates, dies, parts and the like means to produce the design on a production basis. Furthermore, several duplicate template copies of each part or tool are usually required and such original design may therefore need to be redrafted a great number of times prior to its actual construction. 'I'his redrafting has heretofore been accomplished by hand copying methods similar to that employed for the original layout. Such a method of reproduction is obviously very expensive both from the standpoint of labor and time and also extremely inaccurate due to the possibility of human errors.

The principal object of the invention is, therefore, to provide a novel and improved method of reproduction from such master layouts with a prints from the metal master layouts for various uses in the engineering work. Heretofore when such paper prints were desired it has been necessary to redraft the drawings upon paper or cloth from which blue prints could be obtained or to resort to photographic methods for copying the metal layout drawings.

A further object of this invention is accordingly, to provide a method which will enable reproduction of the drawings upon paper from the metal layout sheets without the necessity of redrafting, photographing or the like expensive and time consuming operations;

The invention, accordingly, involves a method of making such reproductions directly upon paper, cloth or the like pervious materials from the metal layout sheets.

Further objects, advantages and features of novelty `of the invention will be made evident hereinafter.

In the drawings which show diagrammatically and by way of illustration a preferred embodiment of the invention;

Figure I is an elevation, sectional view, showing a simple and preferred form of apparatus Figure IV is a view of a typical design or print laid out on the original surface.

Figure V is the result of the method described in this invention showing the reproduction which has been printed from the original surface of Figure IV in conjunction with the apparatus of Figures I, II and III.

In the apparatus which I have shown in Figures I and II, I employ two cooperating parts III and II of a suitable hydraulic press or the like apparatus which are adapted to be moved together under pressure, if necessary, and apart to accomplish results which will be hereinafter described. The member III may be considered as a support or table and the member I I may be termed a head or ram which moves relative to the table I0. Both the table I0 and the head II of the press may be lined with a resilient or a fluid-like material I2 and I3, such as rubber, linoleum,` composite board, or the like. Although it is not necessary that the said lining or pads I2 and I3 be definitely attached to the table III and head II, it is to be understood that the elements must have a relative association substantially that which is shown. The original surface I4 upon which the design is made and the surface I5 on which the design is to be reproduced are inserted between the resilient pads I2 and I3. An electrical connection is made to both surfaces in such a manner that a current is passed between such surfaces. and the other the anode. In order to produce as even a current distribution over the surfaces I4 and I5 as is possible, and in order to simplify the electrical problem, I have found it advisable to install oppositely arranged networks I6 and I6 carried on the padsI I2 and I3 and preferably constructed of relatively thin strips of a high conductivity material such as ternep-late or copper, and to lead the wiring of each to outside terminal posts I'I and I'I to connect them to the electrical source, thus eliminating the necessity of making individual connections to each set of surfaces inserted into the press. The contacter strips of the said network are preferably staggered with respect to one another in order to eliminate any possibility of short-circuits betweenthem in case small surfaces which do not entirely cover the contactor strips of the network are used. Further, it has been found advantageous, and therefore preferable, to install the posts Il and I'I on opposite sides of the apparatus in order to insure an even 'distribution of current.

Figure III shows'a plan View of the table with the various elements necessary to the invention outlined thereon.

Figure IV shows the original surface I4, in this case being a flat metal plate which has been previously coated, painted or sprayed with an insulating paint or otherwise provided with an insulating coating such as an oxide coating formed in situ thereon and forming an insulating surface I8, thus completely isolating the surface I5 from any possible contact with surface I4 when they are placed together in the press. A design, layoutor print I9 which it is desired to reproduce is then scratched, scribed or scored through the insulating surface I8 and into the original metal plate I4. The insulation coating I8 is thus removed along the line of the scratches forming the design I9. The thus scribed metal plate is then wet with a solution or electrolyte 20, preferably ferrous or manganese chloride or sulfate,

and squeezed by means of the apparatus into close a contact with the surface of an uninsulated plate I5 upon which the reproduction or design is to be made. An electrical current 2| is then applied to the elements I and I 5 as the anode and cathode respectively, resulting in the formation of the reproduction 22 upon the plate I5.

While aqueous solutions ofthe ferrous or manganese chlorides or sulfates mentioned above comprise the preferred marking agents, many other materials may be employed. For example, a solution of a salt of substantially anymetal which can be deposited electrically, such as iron, copper, Zinc, tin, etc., will deposit a film of metal when the sheet to be marked is made the cathode; It is advantageous but not essential for the cation of the salt to be of a differently colored metal than the sheet to -be marked. Also, substantially any One plate then becomes the cathode acidorsalt, even of a metal which does not electrolytically deposit, can be employed to carry metal fromra marking plate to the plate to be marked. By making the plate to be marked the anode, similar solutions can be employed to electrolytically etch this plate, or, by using an alkaline solution, the plate to be marked can be subjected to anodic oxidation. In the latter case, alternating current can be employed. Thus, substantially any conducting solution is effective as a marking agent to form a deposit upon or change the appearance of the plate to be marked at portions corresponding to the conducting portions of the master plate so as to transfer the design.

Figure V shows the reproduction 22 of the design I9 which has been formed by means of the invention described herein. It will be noted that by means of an electrolytic action, there has been a visual alteration of the surface of the reproduction plate I5 by etching, oxidation, deposition of metal from the electrolytic solution or transfer of the material from the original surface I4 to the reproduction plate I5.

I have found by my experiments and research that it is possible to insert between the original surface lll, and the reproduction surface I5, a sheet of flexible pervious material 23, such as paper, cloth or any similar fibrous, non-conductive material, without substantially affecting the process. In this manner a print is made on the flexible material 23 as well as on the reproduction plate I5. It is, therefore, possible to not only make a reproduction on the metal surface I5 ,but it is possible to obtain prints on flexible material such as paper and the like at the same time and during the same operation. This is advantageous in mrany respects, notably that it produces a record on paper which can be checked prior to further processing the reproduction plate i5. This arrangement is shown in Figure I.

I have also found by experiment and research that by means of certain solutions or electrolytic uids in association with the apparatus and invention herein described, I can produce a print, similar to the common blue-p-rintfin a simple, cheap and accurate manner. This is accomplished by dipping the paper in la primary solution, preferably of iron and ammonium citrates, due to the cheapness of these substances, or a similar fluid, subjecting it t0 the electrolytic proces-s of this invention, and then developing in a solution of potassium ferric cyanide. Transfer of material is not necessary in this case. Upon completion, the paper is taken out of the pres-s, washed and dried. This process enables one to print directly from the surface of the metal plate. Furthermore, it enables one to obtain a plurality of prints in one o-pertaion, if desired.

As a further example of the adaptation of this process to the making of paper prints direct from the scribed metal plate drawing, it has been found that such paper print may be made by wetting the -surface of the said original scribed plate I4 and saturating the paper with a solution of a solulble salt of an organic or non-organic lalkali metal salt whose corresponding silver salt is also soluble. The thus saturated paper is then placed between the plate I 4 and an oppositeV plate of silver or a metal plate having this inner contacting surface adjacent the paper coated with a layer of silver, and the whole assembly comprising the two plates and the intermediately positioned paper placed in the press in` the position shown at lil, I5 and 23 in Figure I. Pressure is then rapplied by the press to force the original plate I and the silver coated plate I5 in close contact with the intermediate paper 23 as shown in Figure II, and aV unidirectional current of approximately two (2) volts potential difference is then applied to the plates through the terminals I 'I and |11 for approximately ten seconds. The polarity should be such that the metal plate I4 carrying the design is the cathode while the silver plate I5 is the anode. The resulting elect-rochemical reaction produces Vin the paper dark lines of silver oxide corresponding exactly with the contacting scribed design on the original metal sheet Ill. The paper may then be removed from the plates in the press and immediately washed and dried without need of developing and xing. The resultant dark line print may then be u-sed directly or may be employed as a master tracing from which a plurality of blue prints or the like copies can readily be made by the usual contact printing method. In this process the silver oxide is found to be precipitated or electrically deposited in the lines throughout the thickness of the paper which results in an opaque line which is particularly advantageous in obtaining sharp and contrasting duplicate contact prints therefrom.

Examples of so-me of the metal salts which may be employed in the before described paper printing process are the soluble nitrates and sulfates of the alkali metals, lithium, sodium and potassium, and of the alkaline earths such as calcium and magnesium. Of these the sulfate and especially the nitrate of potas-sium and sodium are particularly satisfactory. Suitable -metal organic salts comprise sodium and potassium acetates.

A similar process may Abe carried on by employing, instead of silver, ananode plate of copper or any metal below copper in the electromotive series.

It has also .been found that this process of making paper prints from scribed metal plates carrying an insulating coating as hereinbefore mentioned mfay be performed in the manner just described but employing water or a peroxide of hydrogen, sodium, or potassium, or other compound which readily yields oxygen by electrolysis. For example, the surface of the original scribed plate I4 from which a print is desired, and the paper upon which the print i-s to be made may be wetted with a solution of hydrogen peroxide and the paper then pressed between the said pllate I4 and the silver coated plate I5 in the press and the electric potential applied as before described. The resultant electrochemical reaction will produce a black silver peroxide design print upon the paper corresponding to that carried in the scribed insulating coating of the layout plate I4.

It has also been found particularly advantageous to employ an electrolyte solution comprising a mixture of a nitrate and a peroxide such as, for example, equal volumes of an aqueous solution of three percent (3 %l hydrogen peroxide and an aqueous solution containing one and onehalf (1%) pounds of sodium nitrate per gallon. This electrolytic mixture results in a particularly dense black line in the paper.

A similar process may be carried on by employing, instead of silver, an anode plate of copper or any metal below copper in the electromotive series. An electrolyte of phosphoric acid may also be used in connection with these metals.

While hereinbefore, for convenience of illustration, the reproduction of the design upon paper has been described in connection with this invention, the method is equally applicable to the reproduction of such designs upon cloth sheets or upon bodies of pulpy or other suitable pervious materials.

While it is ordinarily not necessary to do so, the lines printed upon the paper or cloth in the before mentioned processes, especially those containing silver, may be darkened and rendered more permanent by a supplementary treatment, immediately after printing, with a solution of a sodium sulfide. This treatment is effective in connection with all of the before mentioned metal salt solutions but particularly so when the print has been made with a silver salt solution.

A relatively thin translucent type of velum tracing paper may be employed in these processes.

The processes which I have described herein may be adapted to use with a lofting board. A lofting board is used by many industries in order to sketch up contours, water-lines, etc. in relatively large scale in order to further their manufacturing process. Many times the templates and jigs for the various parts of the ship or airplanes are made from such lofting work. This invention can be applied to such Work by means of a portable apparatus which can be taken to the lofting board and prints upon metal, paper or cloth made directly therefrom, or, if preferable, thev lofting board can be made in sections, the sections taken up and transferred to the reproduction apparatus to be adapted to the process herein described.

It will be apparent that the apparatus and method of the present invention is not limited to the marking or printing on flat surfaces but that a properly formed master marking element can be similarly caused to register with curved or irregular surfaces on the article to be marked and be pressed thereagainst by any suitable means. Also, a marking means can be formed of relatively thin sheet metal and be caused to conform to the surface of an irregularly shaped article by a press of the type illustrated herein.

It is to be understood that the description and illustration disclosed herein is merely illustrative of one form which this invention may take and is not to be limiting; other variations and modications being obviously possible without departing from the scope of the invention and the appended claims.

I claim:

1. A method of reproducing a design which comprises forming a layer of insulation upon the surface of a rst member of electrically conducting material which constitutes a cathode, removing portions of said insulation and thereby exposing the surface of said electrically conductive material in an outline corresponding to the form of said design, transferring said design to the surface ofY a second member by wetting said second member with a solution of an alkali metal salt of the group consisting of the nitrates, sulphates, and acetates of the alkali metal, said second member being of non-conductive, fibrous material and being pervious to said solution, pressing said second member containing said solution between the surface of said rst member carrying the design and a third member constituting an anode and having a silver surface of contact with said second member, and passing an electric current through said second pervious member between said first and third members at the points where said insulating layer is removed from said rst member.

2. A method according to claim'l in which the said second member of pervious material is a paper sheet.

3. A method according to claim 1 in which said second member of pervious material is a cloth sheet.

4. A method according to claim 1 in Which the alkali metal salt is sodium nitrate.

5. A method according to claim 1 in which the alkali metal salt in said solution is sodium nitrate and in which said solution contains hydrogen peroxide.

CLARENCE O. PREST.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,739,657 Shemitz Dec. 17, 1929 1,844,928 Slepian Feb. 9, 1932 1,902,213 Brockway Mar. 21, 1933 238,931 Leggs Mar. 15, 1881 670,510 Friese-Greene Mar. 26, 1901 OTHER REFERENCES Korrosion and Metallschutz, 16 Jahrgang, 1940, Number 10, pages 341, 342, 343, 344.

Television, Volume I, Number 2, June 1928I` page 20. 

